When it was first created, the graffiti featured Prof Hawking’s portrait and a design which could resemble a black hole – with reference to the physicist’s love of the universe.

There was also a silhouette of the theoretical physicist in his wheelchair, above the words ‘be curious’ – a nod to Prof Hawking’s popular phrase “remember to look up at the stars, not down at your feet”.

It is thought that part of the graffiti design was painted over on Thursday (April 5).

The portrait of Prof Hawking remains - but the rest has now been altered.

The change was spotted by Cambridge resident Siobhan Holmes, who also took photos to show how the design had changed.

She told the News: "The tribute was really beautiful...and now this. The night sky mural has been covered.

"It was really upsetting to see, as the artwork is so beautiful. It’s close to my friend's flat and liked to see it while walking to university."

Part of the Stephen Hawking graffiti tribute has been painted over (Image: Siobhan Holmes)

But Prof Hawking's condition was first diagnosed when he was 22, and he was not expected to see his 25th birthday.

Despite being wheelchair-bound and almost completely paralysed and unable to speak without aid, he wrote a plethora of scientific papers that earned him comparisons with Albert Einstein and Sir Isaac Newton.